JPH08158933A - Four-cycle engine - Google Patents

Abstract

PURPOSE: To enable miniaturization through the integration of cylinder heads even if a number of valves are employed. CONSTITUTION: In a 4-cycle engine 1 in which each cylinder has three inlet valves and the inlet valves and exhaust valves are opened and closed respectively by cam shafts 19, 20 freely rotationally placed on cylinder heads 5, one plug hole 27 and three inlet-valve lifter portions (lifter holes 17-1, 17-2) are placed in the area of each cylinder which is surrounded by the head bolt holes 35, 36 of the cylinder head 5. Also, the center inlet valve is mounted so that its axis is parallel to the axis of the cylinder or opens in the direction of the cylinder. Then the inlet side cam shaft 19 and the three inlet side lifter holes 17-1, 17-2 can be brought close to the center of the cylinder head 5, so that the cylinder head 5 can be made compact, and that the 4-cycle engine 1 can be made smaller and compact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke engine having three intake valves for each cylinder.

[0002]

2. Description of the Related Art In recent years, multivalve has been promoted as one means for increasing the speed of a 4-cycle engine. For example, a so-called 5-valve engine having three intake valves and two exhaust valves for each cylinder has appeared. There is.

[0003]

However, as the number of valves increases, interference between the valve lifter and the head bolt and the like in the cylinder head and the position of the head bolt become problems. To avoid these problems, the cylinder head is enlarged or the two-stage structure is adopted. Therefore, the number of parts of the cylinder head and the number of assembling steps increase, the structure becomes complicated, and the cost increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a four-cycle engine in which the cylinder head can be downsized as an integral structure even if the number of valves is increased. is there.

[0005]

In order to achieve the above object, the invention according to claim 1 is provided with three intake valves for each cylinder, and the intake valves are provided by a camshaft rotatably arranged on a cylinder head. In a four-cycle engine that opens and closes exhaust valves, one plug hole and three intake valve lifters are arranged in a region surrounded by the head bolt of the cylinder head for each cylinder, and the central intake valve has its axis line. It is characterized by being arranged so as to be parallel to the cylinder center axis or open in the cylinder direction.

According to a second aspect of the invention, in the first aspect of the invention, the diameter of the central intake valve and its lifter is smaller than the diameters of the other intake valves and their lifters.

According to a third aspect of the present invention, in the first or second aspect of the invention, the throat portions of the intake passages on both sides of the cylinder head of each cylinder are projected toward the exhaust side with respect to the center of the cylinder so that intake air on both sides is increased. It is characterized in that a squish area is formed between the port and the central intake port.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the axial centers of the intake valves and lifters on both sides of each cylinder are offset with respect to the center line in the width direction of the cam. Characterize.

[0009]

According to the first aspect of the invention, the camshaft on the intake side and the lifter portion of the intake valve can be brought closer to the center side of the cylinder head, so that the cylinder head can be made compact and the total of four cycles can be achieved. The engine can be made compact and compact.

According to the second aspect of the present invention, the amount of the air-fuel mixture that flows into the cylinder through the central intake valve is limited, so that the air-fuel mixture that flows through the other intake valve into the cylinder is used. The reduction of tumble (vertical swirl) that occurs is minimized.

According to the third aspect of the invention, the throat portions of the intake passages on both sides of each cylinder are brought closer to the exhaust side, and a required squish area is secured between the intake ports on both sides and the central intake port. It is possible to enhance the combustion efficiency of the air-fuel mixture by promoting the stirring of the air-fuel mixture in the cylinder while making the cylinder head compact.

According to the fourth aspect of the present invention, the dimension of the cylinder head in the lengthwise direction can be reduced to make it compact.

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a plan view of an essential part of a cylinder head of a four-cycle engine according to the present invention, and FIGS. 2, 3, and 4 are cross-sectional views taken along lines AA, BB, and CC of FIG. 1, respectively. FIG. 5, FIG. 5 is an enlarged detailed view of FIG. 1D portion, FIG. 6 is a vertical cross-sectional view of the main portion of the same 4-cycle engine, FIG.
8 is a perspective view of the bottom surface of the cylinder head, and FIG. 9 is a plan view of the piston.

The four-cycle engine 1 according to this embodiment is a multi-cylinder engine in which a plurality of cylinders are arranged side by side.
As shown in FIG. 2, a piston 3 is slidably fitted in a cylinder 2a formed for each cylinder in the cylinder block 2, and each piston 3 is rotatably arranged below the piston 3 (not shown). It is connected to the crankshaft via a connecting rod 4.

A cylinder head 5 is attached to the upper portion of the cylinder block 2, and the upper portion of the cylinder head 5 is covered with a cylinder head cover 6.

Thus, the four-cycle engine 1 according to this embodiment has three intake valves 7- on the intake side for each cylinder.
1, 7-2 (see FIGS. 2, 3 and 6) and two exhaust valves 8 (see FIGS. 3 and 6) on the exhaust side are so-called five-valve engines. For each cylinder, three intake passages 9-1 and 9-2 (see FIGS. 2, 3 and 6) and two exhaust passages 10 on the exhaust side (see FIG. 3) are provided.
And FIG. 6) are formed. And the intake passage 9
The intake valves 7-1 and 9-2 are opened and closed by the intake valves 7-1 and 7-2, and the exhaust passage 10 is opened and closed by the exhaust valve 8 at appropriate timings.

By the way, the intake valves 7-1 and 7-2
And exhaust valve 8 are valve guides 11-1, 11-2, 1
2 are slidably inserted and supported respectively, and the valve lifters 13-1, 13-2, 14 are provided above them.
Are provided respectively. The intake valves 7-1 and 7-2 and the exhaust valve 8 have springs 15-.
It is urged toward the closing side by 1, 15-2 and 16, respectively. In this embodiment, the intake side valve lifters 13-1 and 13-2 are provided with inner pads 13a inside them (see FIGS. 2 and 3), and the exhaust side valve lifter 14 is provided with these inner pads 13a. The outer pad 14a is provided on the outer side (upper surface) (see FIG. 3).

The intake side valve lifter 13-
1, 13-2 are slidably fitted in three lifter holes 17-1, 17-2 (see FIGS. 1 to 3 and 6) formed for each cylinder on the intake side of the cylinder head 5, The exhaust-side valve lifter 14 has two lifter holes 18 (FIGS. 1 and 3) formed on the exhaust side of the cylinder head 5 for each cylinder.
And see FIG. 6). As shown in FIG. 1, the walls 5f of the lifter holes 18 on the exhaust side of the adjacent cylinders are formed independently, while the walls 5e of the lifter holes 17-2 on the intake side of the adjacent cylinders are formed. The cylinder heads 5 are connected to each other, whereby the rigidity and compactness of the cylinder head 5 are increased.

On the other hand, as shown in FIGS. 1 and 6, camshafts 19 and 20 are arranged in parallel with each other on the intake side and exhaust side of the upper part of the cylinder head 5, and the intake-side camshaft 19 is The lifter hole 17- of the cylinder head 5
Bearing portions 5 formed on both sides of the bearing 1 so as to sandwich the bearing 1.
a, a bearing cap 21 (see FIGS. 1 to 4 and 6) attached thereto, and bearing portions 5b (only one of which is shown in FIG. 1) formed at both ends of the cylinder head 5 and The journal portion is rotatably supported by a bearing cap (not shown) attached.
Further, the camshaft 20 on the exhaust side is provided with a bearing portion 5c formed between the lifter holes 18 of the cylinder head 5 and a bearing cap 22 (FIGS. 1 to 4).
And FIG. 6) and a bearing portion 5d (only one of which is shown in FIG. 1) formed at both ends of the cylinder head 5 and a bearing cap (not shown) connected to the bearing portion 5d so that the journal portion is rotatably supported. Has been done. Incidentally, FIG.
Further, in FIG. 3, 38 and 39 are oil holes for supplying oil to the journal portions of the camshafts 19 and 20, respectively.

The intake side camshaft 19 has a cam 19 slidingly contacting the valve lifters 13-1 and 13-2.
a is formed, and a cam 20a that slidably contacts the valve lifter 14 is formed on the camshaft 20 on the exhaust side (see FIGS. 3 and 6).

Further, as shown in FIG. 1, the camshaft 1
Sprockets 23 and 24 are attached to the respective ends of 9 and 20, and a timing belt 25 is wound between the sprockets 23 and 24. A variable valve timing device (VVT) 26 is attached to the end of the camshaft 19 on the intake side.

When the intake side camshaft 19 is rotationally driven by a crankshaft (not shown), the rotation is transmitted to the exhaust side camshaft 20 via the sprocket 23, the timing belt 25 and the sprocket 24. As the cam shafts 19 and 20 rotate, the cams 19a and 20a formed on them respectively open the intake valves 7-1 and 7-2 and the exhaust valve 8 at appropriate timings. The intake passages 9-1 and 9-2 and the exhaust passage 10 are opened and closed at appropriate timings to perform predetermined gas exchange.

Further, as shown in FIGS. 1 and 2, one plug hole 27 is formed in the center of the cylinder head 5 for each cylinder so as to be inclined upward toward the exhaust side. A spark plug 28 (see FIG. 2) is provided in the hole 27.
(See reference) is inserted and screwed to the cylinder head 5. Then, the plug hole 2 on the upper part of the cylinder head 5
Sand removing holes 29 (see FIG. 4) are formed between the holes 7, and the sand removing holes 29 are closed by plug bolts 30 (see FIG. 1).

In the four-stroke engine 1 according to the present embodiment, as shown in FIG. 6, the intake side of the cylinder head 5 is connected to the intake manifold 31 connected to the intake passages 9-1 and 9-2. On the exhaust side, an exhaust manifold 32 is connected to the exhaust passage 10. The intake manifold 31 is provided with a control valve 33 (see FIG. 7) for generating a tumble (vertical swirl) of the air-fuel mixture in the cylinder 2a of each cylinder. An injector 34 for injection is attached.

Next, the gist of the present invention will be described.

In this embodiment, the cylinder head 5 is integrally formed by casting, and the cylinder head 5 has a plurality of head bolt holes 35 and 36 formed on the intake side and the exhaust side (see FIGS. 1 and 4). (Refer to FIG. 1), the head block is attached to the cylinder block 2 by a head bolt (not shown).
Are formed on the outside (on the left side in FIG. 1) at a proper pitch so as to sandwich the lifter holes 17-1 and 17-2 of each cylinder, and the head bolt holes 36 on the exhaust side connect the lifter holes 18 of each cylinder. It is formed so as to be sandwiched between these inside (on the left side in FIG. 1) at an appropriate pitch.

In this embodiment, therefore, the camshaft 19 on the intake side is moved toward the center side (cylinder center side) of the cylinder head 5 in order to make the cylinder head 5 compact and downsize the entire engine 1. The camshaft 19 and intake side lifter holes 17-1, 17-
2 is the inside of the head bolt hole 35 on the intake side (right side in FIG. 1)
It is located in.

Therefore, in the present embodiment, as shown in FIG. 1, the two head bolt holes 35 on the intake side and the two head bolt holes 36 on the exhaust side are formed by connecting the respective center points of the respective cylinders. One plug hole 2 in the rectangular area
7 and the lifter portions of the three intake valves 7-1 and 7-2 (that is, the lifter holes 17-1 and 17-2) are arranged.

As shown in FIG. 3, the two intake valves 7-2 on both sides of the central intake valve 7-1 in each cylinder have their axes L2 in the direction of the cylinder 2a with respect to the cylinder center axis M. Although it is arranged to be closed (downward in FIG. 3), as described above, the intake-side camshaft 19 and the lifter holes 17-1 and 17-2 are brought closer to the center side of the cylinder head 5, so that each cylinder The intake valve 7-1 at the center of
As shown in FIG. 2, the axis L1 is the cylinder center axis M.
It is arranged so as to open in the direction of the cylinder 2a (downward in FIG. 2). If structurally possible, the central intake valve 7-1 may be arranged parallel to the cylinder center axis M.

Further, as described above, the intake side camshaft 1
9 and the lifter holes 17-1 and 17-2 are moved closer to the center of the cylinder head 5, as a result, as shown in FIGS. 3 and 7, the throat portions 9-2a of the intake passages 9-2 on both sides of each cylinder are shown.
Is cylinder center axis M (Fig. 3) and cylinder center line N
Only e is projected to the exhaust side with respect to (FIG. 7). As a result of the throat portions 9-2a of the intake passages 9-2 on both sides being brought closer to the exhaust side in this way, as shown in FIG. 7, the intake ports 9-2-1 on both sides and the intake port 9-1-1 in the center are shown. A predetermined squish area S1 is formed between the piston and the piston 3.

Thus, in this embodiment, the central intake valve 7-1 and its valve lifter 13- are provided for each cylinder.
The diameter of 1 is the intake valve 7-2 on both sides and its valve lifter 1
It is set smaller than the diameter of 3-2, but this is for the following reason.

That is, as described above, the central intake valve 7-
As a result, 1 is inclined in the opposite direction to the intake valves 7-2 on both sides, and as a result, the air-fuel mixture flowing from the central intake port 9-1-1 into the cylinder 2a receives the intake ports 9-2- on both sides.
1 acts to cancel the tumble (vertical swirl) generated by the air-fuel mixture flowing into the cylinder 2a from the central intake port 9-1 in order to suppress the action as much as possible.
This is to limit the supply amount of the air-fuel mixture from -1.

Further, in this embodiment, as shown in detail in FIG. 5, the axial centers of the intake valves 7-2 and their valve lifters 13-2 on both sides of each cylinder are set with respect to the center line K in the width direction of the cam 19a. By offsetting e1 and e2 on both sides thereof, it is possible to reduce the dimension of the cylinder head 5 in the length direction and to make it compact.

On the other hand, as shown in FIG. 1, the camshaft 20 and the lifter hole 18 on the exhaust side are the head bolt holes 3 on the exhaust side.
6, the exhaust valve 8 is inclined so that its axis L3 is closed in the cylinder 2a direction (downward in FIG. 3) with respect to the cylinder center axis M, as shown in FIG. Are arranged. Then, as shown in FIG. 7, a squish area S2 is formed between the exhaust ports 10-1 on the lower surface of the cylinder head 5, and as shown in FIG. A cutout groove 3a is formed for flowing the air-fuel mixture whose flow velocity has been increased by S2. A state in which the bottom surface of the cylinder head 5 is viewed obliquely from below is shown in FIG.

By the way, as shown in FIG. 1, a plurality of bolt holes 37 are formed in a zigzag shape in the longitudinal direction (left and right direction in FIG. 1) in the center of the cylinder head 5, and the cylinder head cover 6 ( 6) is attached to the upper surface of the cylinder head 5 by a bolt (not shown) screwed into the bolt hole 37.

As described above, in the present embodiment, the intake side camshaft 19 and the lifter holes 17-1 and 17-2 are brought closer to the center side of the cylinder head 5, and the intake side camshaft 2 is provided for each cylinder.
1 in a rectangular area formed by connecting the center points of one head bolt hole 35 and two head bolt holes 36 on the exhaust side.
One plug hole 27 and three lifter holes 17-1, 17
Since -2 is arranged, the cylinder head 5 can be made compact, and the 4-cycle engine 1 can be made compact and compact.

Further, since the head bolt holes 35 and 36 do not overlap with the cam shafts 19 and 20 in a plan view, the assemblability of the cylinder head 5 is enhanced, and especially the cam shafts 19 and 20 are attached to the cylinder head 5. The cylinder head 5 can be assembled to the cylinder block 2 in a state of being assembled in advance.

Furthermore, in this embodiment, the throat portions 9-2a of the intake passages 9-2 on both sides of each cylinder are moved closer to the exhaust side, and the intake ports 9-2-1 on both sides and the central intake port 9 are arranged.
Since the required squish area S1 is secured between 1-1 and 1-1, the cylinder head 5 can be made compact,
The combustion efficiency of the air-fuel mixture can be increased by promoting the agitation of the air-fuel mixture in the cylinder 2a.

The four-cycle engine 1 according to this embodiment
In the above, it is also possible in design to attach an injector for in-cylinder injection to the side wall of the cylinder head 5 on the intake side.

[0041]

As is apparent from the above description, claim 1
According to the described invention, the camshaft on the intake side and the lifter portion of the intake valve can be brought closer to the center side of the cylinder head, so that the cylinder head can be made compact, and in turn, the 4-cycle engine can be made compact and compact. The effect of being able to do is obtained.

According to the second aspect of the present invention, the amount of the air-fuel mixture flowing into the cylinder through the central intake valve is limited, so that the air-fuel mixture flowing through the other intake valve into the cylinder is controlled. The effect that the reduction of the generated tumble (vertical swirl) is minimized is obtained.

According to the third aspect of the invention, the throat portions of the intake passages on both sides of each cylinder are brought closer to the exhaust side, and a required squish area is secured between the intake ports on both sides and the central intake port. The effect that the combustion efficiency of the air-fuel mixture can be improved by promoting the agitation of the air-fuel mixture in the cylinder while making the cylinder head compact.

According to the fourth aspect of the invention, there is an effect that the dimension of the cylinder head in the lengthwise direction can be reduced to make it compact.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of a cylinder head of a 4-cycle engine according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

4 is a cross-sectional view taken along the line CC of FIG.

FIG. 5 is an enlarged detailed view of a portion shown in FIG. 1D.

FIG. 6 is a vertical cross-sectional view of a main part of a 4-cycle engine according to the present invention.

FIG. 7 is a sectional view taken along line E in FIG.

FIG. 8 is a perspective view of the bottom surface of the cylinder head of the 4-cycle engine according to the present invention.

FIG. 9 is a plan view of a piston of a 4-cycle engine according to the present invention.

[Explanation of symbols]

 1 4-cycle engine 5 Cylinder head 7-1, 7-2 Intake valve 8 Exhaust valve 9-1, 9-2 Intake passage 9-2a Throat part of intake passage 9-1-1, 9-2-1 Intake port 10 Exhaust passage 13-1, 13-2 Valve lifter 17-1, 17-2 Lifter hole 19,20 Camshaft 27 Plug hole 35, 36 Head bolt hole e Intake passage throat projection amount e1 Intake valve offset amount e2 Valve lifter Offset amount K Cam width center line L1, L2 Intake valve axis M Cylinder center axis S1, S2 Squish area

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Claims (4)

[Claims] 1. A four-cycle engine in which three intake valves are provided for each cylinder, and the intake valve and the exhaust valve are opened and closed by a camshaft rotatably arranged on the cylinder head, and the head of the cylinder head is provided for each cylinder. One plug hole and three lifter parts of the intake valve are arranged in the area surrounded by the bolt, and the central intake valve is arranged so that its axis is parallel to the cylinder center axis or opens in the cylinder direction. A 4-cycle engine that does. 2. The four-cycle engine according to claim 1, wherein the diameter of the central intake valve and its lifter is smaller than the diameters of the other intake valves and their lifters. 3. A squish area is formed between the intake ports on both sides and the central intake port by projecting throat portions of intake passages on both sides of the cylinder head toward the exhaust side with respect to the center of the cylinder for each cylinder. The four-cycle engine according to claim 1 or 2, characterized in that. 4. The four-cycle engine according to claim 1, wherein the intake valves on both sides of each cylinder and the axial center of the lifter are offset with respect to the center line in the width direction of the cam.